Quick Facts
Origin: Posterior half of iliac crest and iliolumbar ligament.
Insertion: Inferior border of twelfth rib, transverse processes of first to fourth lumbar vertebrae.
Action: Extends and laterally flexes trunk; stabilizes twelfth rib during inspiration.
Innervation: Anterior rami of twelfth thoracic and first to fourth lumbar nerves.
Arterial Supply: Subcostal and lumbar arteries, lumbar branch of iliolumbar arteries.
Origin
The quadratus lumborum muscle originates from the:
- posterior half of the iliac crest;
- iliolumbar ligament.
Insertion
The fibers of the quadratus lumborum muscle travel superomedially and insert onto the:
- inferior border of twelfth rib;
- transverse processes of the first to fourth lumbar vertebrae.
Key Features & Anatomical Relations
The quadratus lumborum muscle is one of the muscles of the abdomen. It is a thick, quadrilateral type of skeletal muscle that contributes to the formation of the posterior abdominal wall.
It is located:
- anterior to the iliocostalis and transversus abdominis muscles;
- posterior to the kidneys, the colon, the psoas major muscle, the lateral arcuate ligament, and the iliohypogastric and ilioinguinal nerves;
- lateral to the lumbar vertebrae and the lumbar intertransversarii muscles.
Actions
The quadratus lumborum muscle is involved in multiple actions:
- during unilateral contraction, it laterally flexes the trunk to the same side;
- during bilateral contraction, it extends the trunk;
- it stabilizes the twelfth rib during inspiration (Standring, 2016).
List of Clinical Correlates
- Transmuscular quadratus lumborum block
References
Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series 41st edn.: Elsevier Limited.
Actions
The quadratus lumborum muscle is involved in multiple actions:
- during unilateral contraction, it laterally flexes the trunk to the same side;
- during bilateral contraction, it extends the trunk;
- it stabilizes the twelfth rib during inspiration (Standring, 2016).
Learn more about this topic from other Elsevier products
Anatomy of the muscles and nerves of the posterior abdominal wall
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Quadratus Lumborum Muscle
The quadratus lumborum muscle, located nearby, should also be examined.
